The present invention relates to a process for decaffeinating coffee beans. More particularly, coffee beans are decaffeinated using solvent systems which comprise benzyl alcohol. In a preferred mode, the benzyl alcohol is "thinned" with an organic solvent which promotes penetration of the benzyl alcohol into the beans. The process is preferably carried out in the absence of chlorinated hydrocarbon caffeine solvents.
A wide variety of solvent systems have been suggested for use in the decaffeination of coffee. For the most part, such solvents comprise either single-phase organic liquids or two-phase mixtures of an organic liquid and water. Other art-disclosed processes involve the use of elevated temperatures and pressures in conjunction with solvents to promote rapid dissolution of the caffeine and its extraction from the whole coffee beans.
A major problem with many potential decaffeination solvents is their ability not only to solubilize caffeine, but also to dissolve amino acids and sugars and remove them from the green coffee beans. Since the amino acids and sugars are the chemical precursors which develop the familiar coffee aroma and flavor during roasting, their removal by a decaffeination solvent is preferably avoided to the extent possible.
The chlorinated hydrocarbon solvents are currently being used by most producers of decaffeinated coffee since they are cheap, relatively volatile, and rather easily recovered, once appropriate plant facilities are built. While caffeine is not particularly soluble in the chlorinated hydrocarbon solvents, as compared with other types of solvents, the economic advantage of the chlorinated hydrocarbons must be presumed, since they are in such wide commercial use. Importantly, the chlorinated hydrocarbons leave sufficient quantities of the amino acid and sugar flavor precursors in the beans so that decaffeinated coffe beverages with adequate (but sub-optimal) flavor and aroma levels are secured.
The history of current government regulations indicates that there is some concern on the part of health care specialists regarding the use of chlorinated hydrocarbons to decaffeinate coffee. Residual levels of materials such as trichloroethylene have been judged to be intolerable in decaffeinated coffee beans and the use of this material as a decaffeination solvent has recently been brought into question.
As can be seen from the foregoing, it would be advantageous to be able to remove caffeine from coffee beans without the need for chlorinated hydrocarbon solvents. Moreover, it would be highly desirable to use, as a decaffeination means, a caffeine solvent which is generally recognized as safe (GRAS) for food use. The use of a GRAS material as a solvent to decaffeinate coffee would alleviate any concerns about untoward physiological effects on the users of decaffeinated products even if minor traces of the solvent were to remain in the decaffeinated coffee beans.
It has now been determined that solvent systems comprising benzyl alcohol (a GRAS material) are quite effective in removing caffeine from coffee beans. Moreover, use of the benzyl alcohol systems does not result in unacceptable losses of flavor precursors. Accordingly, the present invention provides a process for decaffeinating coffee beans which employs benzyl alcohol as a caffeine solvent.